2000 4.7 4x4 - Squealing sound when cold

[jlistunner]

When it's extremely cold outside, say 25 degrees or less, and I start my truck after it has been sitting for a while, I hear a squealing sound coming from the engine. After it warms up, the sound stops. There are no fluids leaking. This just started last winter around February and wasn't as distinct or consistent as now. I thought maybe it was the idle tensioner pulley so I replaced it with a new one along with putting on a new serpentine belt this past summer. I put it in the shop this past Monday but since it was above 25 degrees that morning, they stated they didn't hear anything. I have to wait until I know it's going to definitely be extremely cold before I put it back in the shop.

The sound does seem to resonate around the area of the water pump. Any suggestions would be greatly appreciated.